Innovative public health interventions are necessary to combat the syngergistic devastation emerging from the dual TB and HIV epidemics in many regions of the world. This proposal will build upon a strong, long-standing working relationship between the Johns Hopkins Center for TB Research and the Rio de Janeiro Health Department to train a highly qualified epidemiologist to become an independent public health researcher in international TB and HIV research and to become proficient at designing and conducting clustered randomized trials (CRTs). Through close mehtorship with two exceedingly qualified investigators, specific coursework, and leadership of a large scale clustered randomized trial, this training will be structured and substantial. The faculty at the Center for TB Research is highly distinguished and the epidemiologic instruction available at the Bloomberg School of Public Health is world renowned. The proposed study will determine if the routine detection and treatment of latent TB in HIV-infected patients in HIV clinics in Rio de Janeiro, Brazil, will reduce TB incidence in those clinics; and, determine the independent and combined effectiveness of isoniazid prophylactic therapy (IPT) and antiretroviral (ARV) therapy to reduce TB incidence in HIV-infected patients. The intervention will consist of implementing a comprehensive policy of screening for and treating latent TB in all HIV-infected patients. Approximately 20,000 patients in 29 HIV clinics will be followed for 5 years and the CRT will take a phased-implementation approach to ensure that all participating clinics will eventually have full coverage. TB incidence will be compared between clinics receiving the intervention and those not yet receiving the intervention. The impact of combined ARV and IPT programs is not known, but together these strategies could potentially reduce TB risk to extremely low levels. Mastering the techniques associated with clustered randomized trials will provide the candidate with important tools for exploring new approaches to reducing TB incidence and transmission. This K01 award will provide the epidemiological training and experience necessary to become a successful, independent public health investigator.